A variety of instruments have been provided or proposed in recent years for applying laser radiation to internal body sites. Such instruments typically include a relatively small diameter, elongated, radiation transmitting flexible member or fiber. Typically, the fiber is advanced through an endoscope or other surgical tool into a body cavity, artery, or other body passage to a selected internal treatment location.
Instruments of the above described type may be broadly defined as laser catheters. As used in this specification and in the claims, the term "laser catheter" or "catheter" is intended to broadly include a flexible, or even rigid, instrument for being inserted into a natural or surgically created internal passage or cavity in a body and through which laser energy is transmitted.
A number of designs have been proposed for a laser catheter which can be inserted into a body passage and operated to direct the laser radiation laterally in a 360.degree. beam to the surrounding site in the body cavity. For example, U.S. Pat. No. 4,672,961 discloses a device in which a special, parabolic reflecting surface is employed in conjunction with a plurality of circumferentially spaced optical fibers mounted in a template around a guiding tube, and this assembly is carried within a surrounding tube that slides within a fixed outer tube.
U.S. Pat. No. 4,852,567 discloses a laser tipped catheter in which laser radiation is radially directed by employing a defusing tip on a tapered optical fiber or by employing a conical reflecting surface disposed in the beam path of a plurality of circumferentially spaced optical fibers.
U.S. Pat. No. 4,799,479 discloses a type of laser catheter in which the cladding is removed from an area along the optical fiber and in which the optical fiber core is abraded so that the fiber surface is roughened. This effects a lateral diffusion of the laser radiation.
While the above-discussed designs may function to radiate laser radiation generally transversely of the longitudinal fiber axis, it would be desirable to provide an improved device which more accurately controls the radiation beam and yet does not require special modifications to an optical fiber or complex arrangements of multiple optical fibers.
It would also be advantageous if such an improved device could efficiently transmit the radiation laterally with a minimum of dispersion, attenuation, or other radiation beam losses.
Some designs employ an internally reflecting prism for directing the radiation laterally. See, for example, U.S. Pat. Nos. 4,445,892 and 4,740,047. U.S. Pat. No. 4,445,892 also discloses, as does U.S. Pat. No. 4,785,815 and published PCT application No. PCT/US89/02492, a design for a laser catheter wherein the radiation is reflected laterally by a mirror. In the design disclosed in the U.S. Pat. No. 4,445,892, the optic system can be rotated with respect to the longitudinal axis so as to sweep through a 360.degree. arc. The mirror can also be pivoted on a ball-and-socket joint by means of guide wires. While this design can be effective in applications for which it is intended, it would be desirable to provide an improved laser catheter device which could be efficiently employed in a variety of medical procedures.
In particular, it would be beneficial if such an improved device could provide radiation in a 360.degree. beam via a relatively simple transmission system. It would also be advantageous if such a 360.degree. beam could be moved along the axis of the catheter wile the catheter remains stationary within the body cavity so as to minimize tissue trauma while at the same time permitting irradiation of a selected length of the surrounding body cavity tissue.
Finally, designs have been proposed for incorporating a hollow optic fiber (i.e., a fiber having a tubular configuration) in a medical device in which a wire can be disposed within the central channel of the fiber to allow axial movement of the wire for performing a pre-defined function at the distal end of the fiber. See for example, U.S. Pat. Nos. 4,768,858 and 4,799,479. Although these designs may take advantage of the central channel of the hollow optic fiber, it would be desirable to incorporate a hollow optic fiber in an improved design wherein laser radiant energy can be efficiently directed substantially transversely of the longitudinal axis and wherein a selected site can be efficiently irradiated along the axis.
The present invention provides an improved laser radiation delivery method and catheter suitable for coupling to a laser source to direct radiant laser energy laterally to a selected body cavity site, and the invention can accommodate designs having the above-discussed benefits and features.